Obesity is a major public health concern. Because obesity is widely prevalent, leads to a myriad of personal and social burdens and, once developed, is difficult to treat, experts emphasize the need for prevention. Among the recommended strategies enumerated in the NIH Strategic Plan for Obesity Research are interventions that target developmental periods of high risk and seek to modify known risk factors for obesity development. Young adulthood represents a developmental period of special risk for weight gain and obesity. Binge eating (overeating with loss of control) is an important modifiable risk factor for obesity development. Binge eating is common in young adults across gender and race/ethnicity groups: about 10% report binge eating at least 1/week. Nationally, about 40% (> 12 million) of 18- to 24- years-olds attend college, making colleges an opportune environment for reaching at-risk individuals. Consistent with the goals of the R15 mechanism, this application proposes to a) gather pilot data about the feasibility, acceptability, and efficac of an evidence-based, peer-guided self-help (PGSH) program targeting binge eating to prevent student weight gain; b) develop research and intervention materials that are suited in content and delivery to the college lifestyle; and c) provide meaningful research involvement for undergraduates. To achieve these aims, we propose a randomized clinical trial testing the efficacy of an eight-session PGSH program targeting binge eating regarding two primary outcomes (cessation of binge eating and change in BMI since randomization) and several secondary outcomes at post-treatment and a six- month follow-up. We plan to recruit men and women from a community college (50%) and a four-year college for randomizing 132 students who report recurrent binge eating into PGSH or pure self-help treatment. Primary outcomes will be measured with rigorous interview (binge eating) and objective (BMI) measures. Program materials will be adapted to reflect an integration of strategies from the obesity and eating disorder fields regarding healthy eating. Upper-class undergraduates will undergo rigorous research training and serve as peer assessors or guides on the study. As an initial step toward our longer-term interest in dissemination/implementation research, this proof of concept study also will examine fidelity of the peer-administered intervention and participants' satisfaction wit PGSH. The innovation derives from applying a proven binge eating treatment to a new target, weight gain prevention; adapting the treatment to peer guidance, a mode of delivery conducive to uptake and broad implementation across campuses; tailoring program content to address unhealthy eating patterns common among college students; and including community college students, a population largely ignored in prior obesity prevention research. Our study will advance public health by creating an evidence-based, targeted, and scalable, highly disseminable obesity prevention program and by educating undergraduate students in health behavior research and evidence based interventions. PUBLIC HEALTH RELEVANCE: This research generates feasibility, acceptability and efficacy data for a peer-guided self-help program targeting binge eating, a modifiable risk factor for obesity development, to prevent weight gain in college students. Young adults are a high risk group for excess weight gain and binge eating is common in this age group (~10%). Annually, over 12 million 18 to 24-year-olds attend college, making colleges an ideal environment for reaching large numbers of at-risk individuals. The proposed work advances public health by developing and evaluating a new strategy for targeted prevention of obesity in young adults who binge eat, a group especially likely to experience rapid and significant weight gain.